Descriptive statistics for N -dimensional closed arrays: A spherical coordinate approach     

Clifford R. Stanley 《Mathematical Geology》1990,22(8):933-956

Recent publications have demonstrated that the composition of a system can be described by the angles which define the vector resulting from the projection of the composition onto the unit hypersphere. Although published trigonometric relationships allow determination of the angles in any number of dimensions, no general hyperdimensional recursive formulae exist for the calculation of these quantities and their variances and covariances. A general methodology for calculating the angles which describe the compositions of systems in any number of dimensions is presented. These angles can be used to calculate statistics (central moments and resultant vectors) describing the central tendency and dispersion among rock compositions, as well as to quantify the angular differences between compositions. Equations that relate the variances and covariances of these angular variables to the variances and covariances of the actual component proportion variables are presented, allowing projection of these measurements from one reference frame to another (cartesian to spherical and vice versa).  相似文献   

岩石化学成分统计分析中的定和变量问题及其解决途径   总被引：2，自引：0，他引：2  

周建文 《岩石学报》1991,7(1):36-43

用岩石化学成分数据之类的定和数组计算相关系数或用于多元统计分析时,由于恒定总数约束的影响,致使结果出现很大的畸变。本文通过定和数组及对应的开数组之间的关系确定了开数组的范围,进而导出“误差对应模型”决定了该开数组,使恒定总数约束影响得以消除,最后用云南金顶铅锌矿的岩石化学分析样作了上述处理,取得了良好的实际效果。  相似文献   

地震序列较强余震灰色及最小二乘拟合预测方法的应用研究   总被引：1，自引：0，他引：1  

平建军  刘荣环  贾炯  曹肃朝  王立军 《华北地震科学》2005,23(1):6-13

在收集、整理1966年～2002年8月我国(主要为大陆地区)183个5级以上地震序列资料的基础上，应用灰色预测和最小二乘拟合预测方法，对每一地震序列较强(显著)余震发震时间进行“硬性”检验预测。结果表明，2种预测方法对7级以上地震序列和6级地震序列的较强(显著)余震具有较好的预测效能，预测效能分别为76．2％和64．7％；而对5级地震序列预测效果则不甚明显。因此，灰色预测和最小二乘拟合预测方法主要着眼于对大(强)地震的较强(显著)余震预测，可望在地震现场大(强)震应急工作中发挥积极作用。  相似文献   

Slowness-backazimuth weighted migration: A new array approach to a high-resolution image     

Tadashi Kito  reas Rietbrock  Christine Thomas 《Geophysical Journal International》2007,169(3):1201-1209

We have developed a new array method combining conventional migration with a slowness-backazimuth deviation weighting scheme. All seismic traces are shifted based on the theoretical traveltime of the scattered wave from specific gridpoints in a 3-D volume. Observed slowness and backazimuth are calculated for each raypath and compared with theoretical values in order to estimate slowness and backazimuth deviations. Subsequently, stacked energy calculated by a conventional migration method is weighted by the slowness and backazimuth deviations to suppress any arrival energy whose slowness and backazimuth are inconsistent with the expected theoretical values. This new method was applied to two P- wave data sets which comprise (1) underside reflections at the 410 and 660 km mantle discontinuities and (2) D" reflections as well as their corresponding synthetic data sets. The results show that the weighting scheme dramatically increases the resolution of the migrated images and enables us to obtain well-constrained, focused images, making upper-mantle discontinuities and D" reflections more distinct by reducing their surrounding energy.  相似文献   

Microseismicity of the ultraslow-spreading Gakkel ridge, Arctic Ocean: a pilot study     

Vera Schlindwein  Christian Müller  Wilfried Jokat 《Geophysical Journal International》2007,169(1):100-112

  相似文献   

New insights into the P- and S-wave velocity structure of the D" discontinuity beneath the Cocos plate     

Tadashi Kito  Sebastian Rost  Christine Thomas  Edward J. Garnero 《Geophysical Journal International》2007,169(2):631-645

Broad-band P - and S -waves from earthquakes in South America recorded at Californian network stations are analysed to image lateral variations of the D"-discontinuity beneath the Cocos plate. We apply two array processing methods to the data set: a simplified migration method to the P -wave data set and a double-array method to both the P - and S -wave data sets, allowing us to compare results from the two methods. The double-array method images a dipping reflector at a depth range from 2650 to 2700 km in the southern part of the study area. We observe a step-like topography of 100 km to a shallower reflector at about 2600 km depth to the north, as well as evidence for a second (deeper) reflector at a depth range from 2700 to 2750 km in the north. Results from the simplified migration agree well with those from the double-array method, similarly locating a large step in reflector depth in a similar location (about 2650 km depth in the south and about 2550 km in the north) as well as the additional deeper reflector at the depth of about 2750 km in the north. Waveform modelling of the reflected waves from both methods suggests a positive velocity contrast for S waves, but a negative velocity contrast for P waves for the upper reflector in agreement with predictions from mineral physical calculations for a post-perovskite phase transition. The data also show some evidence for the existence of another deeper reflector that could indicate a double intersection of the geotherm with the post-perovskite stability field, that is, the back-transformation of post-perovskite to perovskite close to the core–mantle boundary.  相似文献   

气枪震源激发模式及应用   总被引：3，自引：5，他引：3  

罗桂纯  葛洪魁  王宝善  胡平  母红旺  陈颙 《中国地震》2007,23(3):225-232

气枪震源是一种重要的人工地震震源。气枪阵列理论的提出,使得气枪阵列设计技术日趋成熟,并能够在石油勘探和地球物理探测中得到更加广泛的运用。气枪震源在不同领域中应用时,需要不同的组合和激发模式,以适应不同的探测要求。加强主脉冲和加强气泡脉冲,是目前两种主要的气枪激发模式。通过比较研究两种气枪激发模式,讨论各种激发模式在激发时间、气枪间距、频率、分辨率等方面的差异,为气枪震源的广泛运用提供依据。  相似文献   

甫沙-曲吕西地区电磁阵列剖面法研究     

杨军  陈俊湘  徐国强  戴世坤 《新疆地质》2002,20(Z1):121-124

通过对塔里木盆地西南缘甫沙-曲吕西地区电法勘探(CEMP),以电性剖面为主,综合地震、重力、地面地质等资料,运用前陆盆地构造分析学理论,对该区构造式样及局部构造进行了研究,摸索了一套研究复杂构造的方法,弥补了地震勘探的不足.  相似文献   

Broadband synthetic aperture borehole radar interferometry   总被引：1，自引：0，他引：1  

I. Mason  N. Osman  Q. Liu  C. Simmat  M. Li 《Journal of Applied Geophysics》2001,47(3-4)

Trials in mines have established that wideband VHF borehole radars (BHR), working in the 10–100-MHz band, can be used to probe the rockmass between boreholes over ranges from <5 m to as much as 150 m with submeter resolution. There is evidence that ore bodies reflect these radar signals both specularly and diffusely, much as the ground/air interface does when overflown by synthetic aperture radar (SAR). In both SAR and BHR, multiple flight lines, together with diffuse reflections admit the possibility of developing interferometric 3D images of the object. This paper examines the possibility of imaging buried objects in three dimensions by interferometrically combining broadband VHF borehole radar profiles shot in adjacent pairs of boreholes. Broadbanding in BHR has the advantage of releasing the image from 2nπ phase ambiguities, but practically, interferometric borehole radar (InBHR) needs high signal-to-noise ratios (SNR) to avoid noise capture. This means that 3D InBHR is limited to ranges in wavelengths which are less than the rock's attenuation factor Q. Interferometric methods are developed which are capable of mapping ore bodies and other structures in three dimensions. Tangent plane migration methods are developed here in order to reconstruct surfaces that lie in the near-field of sparse interferometric arrays.  相似文献   

The effect of low-velocity sediments on the mislocation vectors of the GRF array   总被引：1，自引：0，他引：1  

F. Krüger  M. Weber 《Geophysical Journal International》1992,108(1):387-393

  相似文献